SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '49de7ee861d89799b94cbb69caff3cff52cf0dd6c8b03dd270e71bfc6f493fcb' 
  AND token = 'xe+P2PG8uBfpIhfHLCY30KqgtT+j2qf3QaJrp0NPZJc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}